Labour’s leaked manifesto draft, published on Wednesday night, said the party would place “peace, universal rights and international law” at the heart of foreign policy, while committing to spend the Nato target of 2% of GDP on defence and to maintaining the Trident nuclear deterrent.

Jeremy Corbyn says Labour manifesto will transform people's lives

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On Friday, the Labour leader, Jeremy Corbyn, is set to give a major foreign policy speech where he will declare “I am not a pacifist”, but say military intervention has become “almost routine in recent times”. Foreign policy has long been one of his personal priorities, especially support for unilateral disarmament and Palestinian rights.

Thornberry said it was “not too late to do Robin’s legacy proud” and reset the UK’s diplomatic course, adding: “Like Robin, we will put human rights back at the heart of Britain’s foreign policy.”

She highlighted plans to halt arms sales to Saudi Arabia until after a UN investigation into alleged war crimes in Yemen, to review all UK contracts with repressive regimes such as Bahrain and a pledge to stand up to countries including China, Turkey and Egypt on human rights.

In Cook’s speech to Foreign Office staff, the then foreign secretary said he would “make Britain once again a force for good in the world” and pledged arms control measures and a focus on human rights and the environment.

“The Labour government does not accept that political values can be left behind when we check in our passports to travel on diplomatic business,” Cook said in 1997. “Our foreign policy must have an ethical dimension and must support the demands of other peoples for the democratic rights on which we insist for ourselves.”

In early 2003, by then leader of the House of Commons, he resigned from the cabinet over the proposed military action in Iraq. In a pointed attack on Theresa May, which also serves to underline Corbyn’s difference over Iraq with Tony Blair’s government, Thornberry criticised May’s decision not to accept the Iraq war was a mistake. “Four times she refused to do so,” Thornberry said.

“If she wins on 8 June, as a fresh act of devotion to Donald Trump, Theresa May will call an immediate vote to authorise military action against the Syrian government,” she went on. “Where Robin Cook came out of the 1997 election wanting ‘to secure the respect of other nations for Britain’s contribution to keeping the peace of the world’, Theresa May goes into this election already planning a unilateral act of war.”

Corbyn’s Labour government would sever the close relationship cultivated by May with the US government, Thornberry said. “From day one, we will stand up to his administration, making clear that the special relationship with America is based above all on shared values and that if Trump continues to ignore and abuse those values, we will criticise him openly, as we would do any other leader,” she said.

In his speech to Chatham House in London, Corbyn is to say: “Waiting to see which way the wind blows in Washington isn’t strong leadership. And pandering to an erratic Trump administration will not deliver stability.”

He will say military action, under international law and as a genuine last resort, “is in some circumstances necessary” but that the “‘bomb first, talk later’ approach to security” has failed.

“So no more hand-holding with Donald Trump; a Labour government will conduct a robust and independent foreign policy made in London,” Corbyn will say.

“This is the fourth general election in a row to be held while Britain is at war and our armed forces are in action in the Middle East and beyond. The ‘war on terror’ which lies behind these interventions has failed. They have not increased our security at home – rather the opposite – and they have caused destabilisation and devastation abroad.”

The former cabinet minister Peter Hain, who served in the Foreign Office with Cook, said he backed the foreign policy rethink in the draft manifesto, especially policies on arms sales.

“This government has watered down the arms control legislation that we introduced, which I as a Foreign Office minister drove forward,” he said. “I think a tightening of that would be welcome. An ethical foreign policy is popular.”

Hain said there was much more to admire in the manifesto beyond foreign policy, including the commitments to affordable housing, elderly social care and investment in the NHS. “They are common sense popular policies,” he said.

“I fought the 1983 election as a Labour candidate, it’s nothing like that. That was unilateral nuclear disarmament, this isn’t. It’s got practical policies that will chime with voters.”